Coffee makers are prevalent in many environments because of society's affection for the beverage, and thus many industries endeavor to offer their customers or patrons coffee as a way to make the experience more enjoyable. From automobile service stations to bookstores, there are few places where a customer cannot get a cup of coffee these days. One such place that patrons can expect a cup of hot coffee is during commercial airplane flights of medium to large distances. Passengers have come to expect this service on commercial flights, and airline manufacturers have developed special coffee brewing machines that meet the specific requirements and limitations of electrical appliances on aircraft.
All coffee brewing apparatus include some form of water heating element to raise the temperature of the water to a level where the oils and extracts of the coffee beans can be released. Water is pumped through a tubing with a resistive heating element that heats the water as it flows through the tubing. The resistive heating element is typically a coiled wire, similar to the element in an electric toaster, that heats up when electricity is run through it. In a resistive element like this, the coil is embedded in a plaster to make it more rugged. The heating element serves multiple purposes, namely to initially raise the temperature of the supply water to brewing temperature, and then when the coffee is made, the heating element keeps the coffee warm.
The resistive heating element may be sandwiched between a warming plate and an aluminum water tube. The resistive heating element presses directly against the underside of the warming plate, and white, heat-conductive materials such as grease make sure the heat transfers efficiently. The coffee maker's power switch turns power to the heating element on and off, and to keep the heating element from overheating there are sensors and fuses. In coffee makers, sensors detect if the coil is getting too hot and, if so, cut off the electrical current. When the coil cools down, the sensor turns the current back on. By cycling on and off like this, coffee brewers keep the coil at an even temperature. Similarly, fuses simply cut the power if the temperature reaches a certain level. Fuses are a safety measure in the event that the main sensor fails. Coffee makers also typically employ a one-way valve. The one-way valve lets cold water into the aluminum tube, but forces the bubbles of boiling water to flow up the brew tube.
The present invention is directed to a flow-through type water heater for a beverage maker, and more particularly to a flow-through water heater for an aircraft galley appliance for making beverage, the appliance having three-phase power capability and a removable baffle core. Most flow-through heating assemblies use a single phase power source to energize the heating element. Examples of such heating assemblies include plasma-sprayed circuit flow-through heaters from Watlow Electric Manufacturing Company of St. Louis, Mo. These heaters receive a flow of water from a water supply and heat the water to a temperature that is appropriate for brewing coffees, teas, espressos, and the like. However, there are several characteristics of such heating units that make them unsuitable for use in aircraft. First, aircraft power systems utilize a three-phase power that cannot be used with the aforementioned single phase heaters. Second, the core of the prior art heating units are fixed, which makes it challenging to determine if deposits are affecting the performance of the heating core. That is, traditional heater assemblies are welded together into a single piece, so the core and end fittings can not be removed. Thus, the inner passage way of the heater that the water flows through cannot be well monitored for hard water scale buildup. In addition, the current baffles are made from stainless steel, which is much heavier than the PEEK plastic used to fabricate the removable baffle core of the present invention. Third, such cores are typically made of a solid metal, adding weight to the beverage maker that is undesirable to aircraft components. Fourth, these cores lack the capability to effectively monitor the temperature of the water inside the core, which can lead to safety concerns as well as inefficiencies in the heating operation.